Results:

A total of 3,999 cases of HZ were recorded among 85,458 seniors with RA during 614,915 person-years (6.5 events/1000 person-years). Comparing these HZ cases to 19,995 RA controls, 21.9% of cases versus 10.8% of controls were exposed to prednisone at the time of infection. Multivariate models demonstrated that risk of HZ was higher among current and past use of all DMARD groups. There was a notable increasing trend for higher risk of HZ with increasing steroid doses. Due to low rates of biologic drug exposures in our sample, the estimated effects of these agents were imprecise, but also consistent with a higher risk.

Conclusions:

Our estimates emphasize an association of anti-rheumatic therapies with the occurrence of HZ. Potential limitations of our study include the possibility of incomplete ascertainment of biologic exposures (private insurance is not represented in public payer database; but this is uncommon) and channelling bias (where persons at highest risk for infections may not be prescribed biologics).